Stamping and welding method and apparatus for forming a hollow or tubular member with high tolerances

ABSTRACT

A method of forming a hollow metal member may include stamping a metal blank to form half shell pieces that are configured to be approximately a half of a hollow metal member and stamping a another metal blank to form a half shell piece that is configured to be approximately the other half of the hollow metal member. The half shell pieces may be aligned to place the edges of the first and second half shell pieces in abutting contact. The half shell pieces may be welded together along seams that are defined at the abutting edges of the first and second half shell pieces. The attached half shell pieces may then be compacted to form the hollow metal member with reduced residual deformation from stamping and welding the half shell pieces.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims benefit and priority under 35 U.S.C. § 119(e) of U.S. provisional application Ser. No. 62/635,220, filed Feb. 26, 2018, which is hereby incorporated herein by reference in its entirety.

TECHNICAL FIELD

This disclosure generally relates to forming methods and processes for hollow or tubular members and, more particularly, to stamping and welding processes for forming hollow or tubular members from metal sheet blanks.

BACKGROUND

Metal tubular members that are formed with a stamping process commonly provide half shells that, after striking, have a springback or residual elastic deformation that results in an imprecise final shape of the stamped half shells. One way that this imprecise final shape of the half shells may be accounted for in the forming a tubular member is to join the half shells together with a lap joint or other form of overlapping seam. These seams commonly provide inaccuracies that are difficult to control for continuously or repetitively forming a precisely shaped part or piece. Another known way to address the issue of springback in half shells is to shape a flange region of the blank and perform at least two strikes on a blank for a deep draw into the blank to avoid elastic deformation, whereby the flanges can be trimmed in a shear die, such as described in U.S. Pat. No. 8,296,922. However, upon welding together abutting edges of the resulting half shells, heat induced deformation may be provided at the seams, especially on thinner metals, so as to create inconsistencies and inaccuracies in the final shape of the part.

SUMMARY

The present disclosure provides a process for forming a hollow metal member or part that involves compacting or re-striking attached shell blanks to form the hollow metal member in a final shape that reduces residual deformation from intermediate stamping and welding processes. There may be residual deformation when forming shell pieces that are stamped from metal blanks, such as metal sheets, where the shell pieces may be configured to be approximately a half of a hollow metal member. Two shell pieces may be aligned to place the edges of the first and second shell pieces in abutting contact for welding the pieces together along the edge abutment seams. There may also be residual deformation or inaccuracies in the attached shell pieces from the welding process. Thus, the attached shell pieces may be compacted, such as at a compacting station, to form the hollow metal member with reduced residual deformation from stamping and welding the shell pieces.

According to one aspect of the present disclosure, a method of forming a hollow metal part includes stamping a first metal blank to form a first shell piece that is configured to be a portion of a desired hollow metal part and stamping a second metal blank to form a second shell piece that is configured to be a remaining portion of the desired hollow metal part. The first and second shell pieces are aligned to place the edges of the first and second shell pieces in abutting contact. The first and second shell pieces are welded together along seams that are defined at the abutting edges of the first and second shell pieces to provide a non-conforming hollow part with residual deformation from stamping and welding the first and second shell pieces. The non-conforming hollow part is then compacted in a die assembly to reduce the residual deformation and to form the desired hollow metal part. Further, the first and second shell pieces may be formed to have an oversized outside profile, such as at least 1 percent greater than a desired outside profile, so that compacting the attached shell pieces reduces the outside profile to the desired outside profile.

According to another aspect of the present disclosure, an apparatus for forming a hollow metal part may provide a stamping station that is configured to stamp at least one metal sheet blank to form first and second shell pieces that are configured to mate together to form a hollow metal part. A welding station may have a fixture configured to align the first and second shell pieces with edges of the first and second shell pieces in abutting contact. Also, the welding station has a welder that is configured to weld the first and second shell pieces together along seams defined at the abutting edges. The welding station forms the hollow metal part with a non-conforming shape due to residual deformation from stamping and welding the first and second shell pieces. A compacting station has at least two die pieces that together are configured to engage around an outside profile of the hollow metal part and apply inward pressure to form the hollow metal part with a desired shape. Optionally, the compacting station may include an internal mandrel that is disposed at a hollow area enclosed by the attached half shell pieces during the compacting of the attached shell pieces.

According to yet another aspect of the present disclosure, a hollow metal part that is formed from two half shell stampings includes an outer wall that extends around a hollow interior area of the metal part and spans between a first end opening and a second end opening of the metal part. A section of the outer wall between the first and second end openings includes a curvature that offsets the first end opening relative to the second end opening. A pair of weld seams extend along opposing portions of the outer wall and between the first and second end openings. The pair of weld seams define an attachment interface of abutting edges of shell stampings that form hollow metal part. The outer wall has a desired shape with a consistent profile that is formed from a finishing compacting press, which reduces residual deformation at the pair of weld seams, such as a result of stamping and welding the shell pieces.

These and other objects, advantages, purposes, and features of the present disclosure will become apparent upon review of the following specification in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a cross-sectional view of a metal sheet blank and a half shell blank that is formed from stamping the metal sheet blank;

FIG. 1B is a cross-sectional view of a metal sheet blank, a pre-trimmed half shell blank that is formed from stamping the metal sheet blank, and edge portions being removed to provide a half shell blank;

FIG. 1C is a cross-sectional view of a metal sheet blank, a pre-trimmed half shell blank that is formed from stamping the metal sheet blank, edge portions of the pre-trimmed half shell blank being removed from the stamped blank, and a half shell blank that is formed by stamping the remaining flanges;

FIG. 2 is a cross-sectional view of a stamped half shell blank, showing the blank in a nominal position and a springback position after stamping;

FIG. 3 is a cross-sectional view of two stamped half shell blanks welded together to form a tubular member; showing a nominal position and a deformed position after welding;

FIG. 4 is a cross-sectional view of two stamped half shell blanks, showing the springback position, welding deformation position, and the combined deformation resulting from each;

FIG. 5 is a cross-sectional view of a post-welding compacting station that has two stamping dies that restrike the welded blanks to remove residual deformation;

FIG. 6 is a perspective view of a tubular member formed with post welding stamping to restrike the welded half shell blanks to provide high tolerance control;

FIG. 7 is an elevation view of the tubular member shown in FIG. 6;

FIG. 8 is another elevation view of the tubular member shown in FIG. 6;

FIG. 9 is yet another elevation view of the tubular member shown in FIG. 6;

FIG. 10 is a perspective view of an additional example of a tubular member having three openings and formed with post welding stamping to restrike the welded half shell blanks;

FIG. 11 is an elevation view of the tubular member shown in FIG. 10;

FIG. 12 is another elevation view of the tubular member shown in FIG. 10; and

FIG. 13 is yet another elevation view of the tubular member shown in FIG. 10.

DETAILED DESCRIPTION

Referring now to the drawings and the illustrative embodiments depicted therein, a method and apparatus is provided for forming a tubular or hollow part or member that is made of metal. The process for forming the hollow metal member 10 (FIGS. 6-9), 110 (FIGS. 10-13) involves compacting or re-striking half shell blanks or pieces 12 that are welded together. The compacting or re-striking forms the hollow metal member 10, 110 in a final shape that reduces residual deformation that may be present from intermediate stamping and welding processes. Initially, a metal blank 14, such as a piece of metal sheet stock, may be stamped to form a half shell blank or piece 12 that is shaped to be approximately a half of the final hollow metal member 10, 110. Accordingly, such as shown in FIGS. 2-5, two half shell blanks 12 a, 12 b may be formed in shapes configured to be attached together along their respective edges to form a hollow metal member 10. The half shell blanks or pieces 12 a, 12 b may be welded together along a seam or seams 16 (FIG. 3) at the abutting edges of the half shell blanks or pieces 12 a, 12 b. As shown in FIG. 5, the welded or attached half shell pieces 12 a, 12 b are then compacted at a compacting station 18 to form the hollow metal member 10 that has reduced or substantially illuminated the residual deformation from the intermediate stamping and welding of the half shell blanks or pieces 12 a, 12 b.

A stamping station may be configured to stamp metal sheet blanks 14 to form half shell pieces that are configured to be approximately a half of a hollow metal member 10. As shown in FIGS. 1A-1C, half shell blanks or pieces 12 may be formed with various processes, which may depend on the material type, sheet thickness, shape and size of the desired half shell piece, or a combination of these and other considerations in the tool and die making process. For example, as shown in FIG. 1A, the metal blank 14 is a piece of sheet metal that, in a single stamping, is formed to the half shell blank or piece 12. Similarly, such as shown in FIG. 1B, the metal blank 14 is a piece of sheet metal that, in a single stamping, is formed to a pre-trimmed half shell blank 20 that has a semi-circular shape with flanges 22 a, 22 b extending from the portion of the pre-trimmed half shell blank 20 that is desired for the final part. The flanges 22 a, 22 b are then trimmed from the desired portion to provide the half shell blank or piece 12, where the edges 24 a, 24 b of the half shell blank or piece 12 may be controlled by a cutting operation. The cutting operation may be performed by a cutting die, a laser cutter, a saw, or other conceivable cutting device.

As another example of a process to form a half shell blank, as shown in FIG. 1C, the metal blank 14 is stamped twice before forming the half shell blank or piece 12. Specifically, the sheet metal blank 14 is formed to a pre-trimmed half shell blank 26 that has a semi-circular shape with flanges 28 a, 28 b extending outward from the portion of the pre-trimmed half shell blank 26 that is desired for the final part. The flanges 28 a, 28 b are then trimmed from the desired portion, but with some of the flange remaining extending outward. The second stamping then bends the remaining portions of the flanges into the final shape of the half shell blank or piece 12. The half shell blanks may also assume various alternative shapes, such as ovular or trapezoidal or other curved or orthogonal shape, to correspond with the shape of the resulting hollow member or part. These processes shown in FIGS. 1A-1C are some examples of ways to form a half shell blank, which each provide at least some springback or residual elastic deformation that draws or biases the formed part partially back toward the flat or planar shape of the metal blank. As shown in FIG. 2, this springback position 30 is the actual position of the half shell piece 12 after formation, while the nominal or desired position 32 is also shown for reference, which may be the position of the blank immediate after forming, but before springback has occurred.

As shown in FIGS. 3 and 4, two opposing half shell blanks or pieces 12 a, 12 b are aligned together to place the edges of the of the half shell blanks or pieces 12 a, 12 b in abutting contact. This alignment may be done in a fixture of a welding station, such that once the half shell blanks or pieces 12 a, 12 b are aligned, they may welded together along seams 16 defined at the abutting edges of the half shell blanks or pieces 12 a, 12 b. For instance, as shown in FIGS. 6-9, the formed seams 16 may be formed in a common plane through the hollow metal member 10, such as between opposing and symmetrical half shell blanks or pieces. Alternatively, in some cases the seams may not be in a common plane, such as defined by unsymmetrical shell blanks or pieces, and may instead have a seam or seams that follow a widest point when dividing the tubular area between the two shell blanks or pieces, such as seams that follows the contour or curvature of the hollow member along opposing sides of the hollow member.

The welding of the seams may be done with a manual or automated welder at the welding station, such as a laser welder or arc welder or the like. Further, such a welding operation may cause some deformation at the seam 16 between the abutting edges of the half shell blanks or pieces 12 a, 12 b, such as deformation induced or at least partially attributable to heat of the welding process. This may be more prominent in certain types of metals and with thinner thicknesses of metal pieces, which can create inconsistencies and inaccuracies that are difficult to predict or control. As shown in FIG. 3, the heat deformation position 34 may be the actual position of the attached half shell blanks 12 a, 12 b after welding, while the nominal or desired position 36 is also shown for reference, which may be the position of the blanks in the fixture prior to welding.

To illustrate the combined potential effect of the springback and heat induced deformation, FIG. 4 illustrates the actual final formed position 38 of the attached blanks, along with the design or nominal position 40 of the final part. To bring the final formed position 38 to or toward the nominal position 40 and thus illuminate or reduce the residual deformation that results from stamping and welding the half shell pieces, a compacting station 18, such as shown in FIG. 5, may utilize at least two die pieces 42 a, 42 b that together are configured to engage around the outside profile or perimeter of the attached half shell pieces 12 a, 12 b and apply inward pressure, via a press attached to one of the die pieces, to form a hollow metal member 10 with a reduced and consistent outside profile or perimeter from the attached half shell pieces 12 a, 12 b. The compacting station 18 may optionally include an internal mandrel 44, such as shown in FIG. 5, which may be disposed at and generally fill a hollow interior area 46 that is enclosed by the attached half shell pieces 12 a, 12 b during the compacting of the attached half shell pieces 12 a, 12 b. It is also contemplated that additional die pieces may be provided, such as to engage the outside profile or perimeter of alternatively shaped cross-sections.

To provide sufficient material for the compacting station 18 to engage and form the desired part, the half shell pieces 12 a, 12 b may be formed to have an oversized outside profile that is greater than a desired outside profile of the resulting hollow metal member 10 formed by the compacting station 18 (FIG. 5). For example, the outside profile of the half shell pieces may be at least 1 percent greater than the desired outside profile or may be 1 to 2 percent greater than the desired outside profile or may less than 5 percent greater than the desired outside profile, where the precise oversized profile that is preferred for a particular hollow metal member or part may depending on the ductility of the metal, thickness of the sheet, or shape of the part, among other factors. In some cases, the outside diameter of the attached half shell pieces may be a distance to measure the outside profile of the attached half shell pieces.

Once welded together and compacted to or toward the nominal shape, the half shell pieces 12 a, 12 b of the hollow metal member 10 together provide an outer wall 48 that extends around the hollow interior area 46 of the metal member 10. The outer wall 48 may have a substantially constant thickness and a generally uninterrupted and continuous outer surface. As shown in FIGS. 6-9, the outer wall 48 spans between the opposing end openings 50 a, 50 b, where a section of the hollow metal member 10 between the end openings 50 a, 50 b includes a curvature that offsets the openings 50 a, 50 b relative to each other, such as shown approximately 90 degrees relative to each other. The accuracy of the positioning of the openings relative to each other can also be improved by the compacting process, as the initial positioning of the openings can be misaligned by springback and welding effects. As shown in FIG. 9, the weld seams 16 may have different lengths and radii of curvature due to being located at opposing portions of the outer wall between the end openings 50 a, 50 b. Accordingly, the compacting process shown in FIG. 5 may also correct curvature variations in the welded half shell pieces 12 a, 12 b, such as a result of the different sized and shaped seam sections. In additional embodiments, it is contemplated that additional openings, such as four or six or twelve more openings, or fewer openings, such as a single opening, may be present in the hollow metal member, where the openings may each interrupt the seam or seam sections that interconnect the half shell pieces.

The openings 50 a, 50 b in the hollow metal member 10, such as shown in FIGS. 6-9, may also have different shapes, such as to correspond with the shape of the desired connection points of the hollow metal member 10, such as circular, oval, trapezoidal, lofted, rectangular, or other shaped openings. For example, as shown in FIG. 6, one opening 50 a has a circular shape and may be configured to be press fit with a tubular component and where the other opening 50 b has an oval shape. Thus, the outer wall 48 of the finished hollow metal member 10 at or near at least one end opening may have an outside surface with a substantially consistent shape or profile, such as a constant diameter about the circular opening 50 a shown in FIG. 8. It is contemplated that additional hollow metal members or parts may be formed with various shapes and openings and it is understood that the hollow metal member or part may be made with various metals, such as stainless steel, high strength steel, ultra-high strength steel, martensitic steel, aluminum, among other conceivable metals.

With reference to FIGS. 10-13, an additional example of a hollow metal member 110 is shown that has an outer wall 148 spanning between three openings 150 a, 150 b, 150C. The hollow metal member 110 also includes two curvatures between the circular end opening 150 a and the oval openings 10 b, 150 c at the opposing end of the hollow metal member 100. The circular opening 150 a is shown approximately 90 degrees relative to each other two oval openings 150 b, 150 c, although it is contemplated that other angular variations may be provided in additional examples. The accuracy of the positioning of the openings 150 a, 150 b, 150 c relative to each other can also be improved by the compacting process, where the initial positioning of the openings can be misaligned from the nominal shape by springback and welding effects.

As further shown in FIGS. 10-13, the half shell blanks or pieces 112 a, 112 b are aligned together to place the edges of the half shell blanks or pieces 112 a, 112 b in abutting contact. This alignment may be done in a fixture of a welding station, such that once the half shell blanks or pieces 112 a, 112 b are aligned, they may welded together along the seams 116 a, 116 b, 116 c defined at the abutting edges of the half shell blanks or pieces 112 a, 112 b. This welding operation may be done with a manual or automated welder at the welding station, such as a laser welder or arc welder or the like. Further, such a welding operation may cause some deformation at the seam 16 between the abutting edges of the half shell blanks or pieces 112 a, 112 b, such as deformation induced or at least partially attributable to heat of the welding process. This may be more prominent in certain types of metals and with thinner thicknesses of metal pieces, which can create inconsistencies and inaccuracies that are difficult to predict or control.

As further shown in FIGS. 10 and 13, the weld seams 116 a and 116 b extend symmetrically from the circular opening 150 a to the oval openings 150 b, 150 c, while the remaining weld seam 116 c extends between the oval openings 150 b, 150 c in a saddle shape. Thus, the compacting process may also correct curvature variations in the welded half shell pieces 112 a, 112 b, such as a result of the different sized and shaped seams.

The openings 150 a, 150 b, 150 c, such as shown in FIG. 10, may also have different shapes, such as to correspond with the desired connection points of the part 110. For example, as shown in FIG. 10, one opening 150 a has a circular shape and may be configured to be press fit with a tubular component and where the other openings 150 b, 150 c have oval shapes. Thus, the outer wall of the finished part 110 at or near at least one end opening may have an outside surface with a substantially consistent shape or profile, such as the diameter about the circular opening 150 a.

There may be residual deformation when forming half shell pieces that are stamped form metal blanks, such as metal sheets, where the half shell pieces are configured to be approximately a half of a hollow metal member. Two half shell pieces may be aligned to place the edges of the first and second half shell pieces in abutting contact for welding the pieces together along the edge abutment seams. There may also be residual deformation or inaccuracies in the attached half shell pieces from the welding process. Thus, the attached half shell pieces may be compacted, such as at a compacting station, to form the hollow metal member with reduced residual deformation from stamping and welding the half shell pieces.

For purposes of this disclosure, the terms “upper,” “lower,” “right,” “left,” “rear,” “front,” “vertical,” “horizontal,” “inner,” “outer,” and derivatives thereof shall relate to the concept as oriented in FIG. 6. However, it is to be understood that the concept may assume various alternative orientations, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in this specification are simply exemplary of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise.

Changes and modifications in the specifically described embodiments may be carried out without departing from the principles of the present invention, which is intended to be limited only by the scope of the appended claims as interpreted according to the principles of patent law. The disclosure has been described in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the present disclosure are possible in light of the above teachings, and the disclosure may be practiced otherwise than as specifically described. 

What is claimed is:
 1. A method of forming a hollow metal part, said method comprising: stamping a first metal blank to form a first shell piece that is configured to be a portion of a desired hollow metal part; stamping a second metal blank to form a second shell piece that is configured to be a remaining portion of the desired hollow metal part; aligning the first and second shell pieces to place edges of the first and second shell pieces in abutting contact; welding the first and second shell pieces together along seams defined at the abutting edges of the first and second shell pieces to provide a non-conforming hollow part with residual deformation from stamping and welding the first and second shell pieces; and compacting the non-conforming hollow part in a die assembly to reduce the residual deformation and form the desired hollow metal part.
 2. The method of claim 1, wherein the first shell piece is configured to be approximately a half of the desired hollow metal part and the second shell piece is configured to be approximately the other half of the desired hollow metal part.
 3. The method of claim 1, wherein the first and second shell pieces are formed to have an oversized outside profile that is greater than an outside profile of the desired hollow metal part.
 4. The method of claim 3, wherein the oversized outside profile has a diameter that is at least 1 percent greater than a corresponding diameter the outside profile of the desired hollow metal part.
 5. The method of claim 1, wherein the die assembly that compacts the non-conforming hollow part includes at least two die pieces that contact substantially entirely around an outer surface of the non-conforming hollow part.
 6. The method of claim 5, wherein an internal mandrel is disposed at a hollow area enclosed by the attached first and second half shell pieces during the compacting of the non-conforming hollow part by the at least two die pieces.
 7. The method of claim 1, wherein the desired hollow metal part includes at least one opening that is configured to be press fit with a tubular component.
 8. The method of claim 1, wherein the desired hollow metal part includes at least three openings.
 9. The method of claim 1, wherein the desired hollow metal part includes a first end opening and a second end opening, and wherein a curved section of the hollow metal part is disposed between the first and second end openings.
 10. An apparatus for forming a hollow metal part, said apparatus comprising: a stamping station configured to stamp at least one metal sheet blank to form first and second shell pieces that are configured to mate together to form a hollow metal part; a welding station having a fixture configured to align the first and second shell pieces with edges of the first and second shell pieces in abutting contact and a welder configured to weld the first and second shell pieces together along seams defined at the abutting edges; wherein the welding station forms the hollow metal part with a non-conforming shape due to residual deformation from stamping and welding the first and second shell pieces; and a compacting station having at least two die pieces that together are configured to engage around an outside profile of the hollow metal part and apply inward pressure to form the hollow metal part with a desired shape.
 11. The apparatus of claim 10, wherein the desired shape of the hollow metal part has a consistent outside profile with reduced residual deformation.
 12. The apparatus of claim 11, wherein the first and second shell pieces are formed to have an oversized outside profile that is greater than the consistent outside profile of the desired shape of the hollow metal part.
 13. The apparatus of claim 12, wherein the oversized outside profile has a diameter that is at least 1 percent greater than a corresponding diameter the consistent outside profile of the desired shape of the hollow metal part.
 14. The apparatus of claim 10, wherein the first shell piece is configured to be approximately a half of the hollow metal part and the second shell piece is configured to be approximately the other half of the hollow metal part.
 15. The apparatus of claim 10, wherein the compacting station has an internal mandrel is disposed at a hollow area of the hollow metal part to prevent the inward pressure from collapsing the hollow metal part when forming the desired shape.
 16. A hollow metal part formed from two shell stampings, said hollow metal part comprising: an outer wall that extends around a hollow interior area of the hollow metal part and spans between a first end opening and a second end opening of the hollow metal part; wherein a section of the outer wall between the first and second end openings includes a curvature that offsets the first end opening relative to the second end opening; a pair of weld seams extending along opposing portions of the outer wall and between the first and second end openings, wherein the pair of weld seams define an attachment interface of abutting edges of shell stampings; and wherein the outer wall has a desired shape comprising a consistent profile that is formed from a finishing compacting press that reduces residual deformation at the pair of weld seams.
 17. The hollow metal part of claim 16, wherein outer wall near at least one of the first or second end openings includes a circular shape configured to be press fit with a tubular component.
 18. The hollow metal part of claim 16, wherein the outer wall defines a third end opening, and wherein at least one of the pair of weld seams intersect the third end opening.
 19. The hollow metal part of claim 16, wherein the shell stampings are formed to have an oversized outside profile with a diameter that is at least 1 percent greater than the consistent profile that is formed from the finishing compacting press.
 20. The hollow metal part of claim 19, wherein the shell stampings defined by the weld seams are configured to be approximately a half of the desired shape of the outer wall of the hollow metal part. 